Method of Securing Skin Graft: A Comparison of Vacuum Assisted Closure Device Versus Bolster Dressing

This randomized controlled trial was conducted at the Department of Plastic and Reconstructive Surgery at Dr. Ruth K.M. Pfau Civil Hospital Karachi from 21st October 2021 to 20th June 2022. Before conducting the study, ethical approval was obtained from Dow University of Health Sciences (DUHS) (IRB-2125/DUHS/Approval/2021/637).

All patients were enrolled via non-probability consecutive sampling. The sample size for the current study was calculated as follows:

Mean graft take for VAC group = 96 ±6 Mean graft take for conventionally treated group = 89±20 (10) Level of confidence = 95% Power = 80% A sample of 140 patients (70 per group) was required to detect mean difference of 7 in graft take between two groups as estimated by using the above parameters through online available calculator Open Epi.

Patients visiting outpatient department and requiring skin graft were admitted to Plastic surgery and recruited into the study with their consent. Study purpose and risk and benefits associated with the procedure were explained to the patient to obtain their consent. Total 70 patients in each group, meeting the inclusion criteria were enrolled. Patients were randomly allocated either to the conventional group or new technique group. Random allocation of patients was done using the SNOSE (sequentially numbered opaque sealed envelope) protocol. Total 140 sequentially numbered opaque sealed envelopes was prepared enclosing the group name with half of the envelop will be enclosing name of group A (VAC group) and other half enclosing the group b (bolster dressing group) and after that envelops was shuffled to ensure randomization.

Skin grafting was performed under general anesthesia. Humby's knife was used to harvest skin graft from donor site. Skin graft was hand meshed and secured to the recipient site circumferentially with absorbable sutures, followed by Tincture of benzoin soaked paraffin gauze layer. For the bolster dressing group, the recipient site was bolstered with wet bulky cotton gauze dressing and wrapped with cotton bandage. 0.9% normal saline was used for moisture. For the Vacuum assisted closure (VAC) Group, two sheets of sterilized VAC sponge that was cut to fit the wound contour were placed with a fenestrated tube between the two layers that was secured to the surrounding skin using tincture of benzoin spray and an adhesive dressing (OPSITE). The VAC was placed at -125mmHg suction and checked for any air leak. Any loss of suction was treated by reinforcing the adhesive dressing over the air leak. The VAC was decompressed and clamped till the patient is shifted back to the ward. Once in ward, The VAC was placed to intermittent -125 mmHg suction for 2 hours and then decompressed for next 2 hours. Bed rest, sling or splint was used for immobilization depending on the location of injury.

Patients were permitted for slight movement for personal hygiene reasons. First dressing change was done on 5th post-operative day. They underwent early change of dressing in case excessive soakage of dressing with blood, serous fluid or foul smelling discharge or pus was present. Dressing of patient was opened on 5th operative day by researcher and then assessed by supervising consultant for percentage of skin graft take and post-operative complications. A pre-designed proforma was designed to collect the data. Patients' data was kept confidential. Medical record no. of patients was tagged with other serial number to assure the confidentiality of the data and only principal investigator had an access to original data.

Data was entered and analyzed by using SPSS version 21. Qualitative variables like gender, socioeconomic status, place of residence, smoking status, medical comorbidities (such as diabetes mellitus and hypertension), graft site, donor site, post-operative complications were presented as frequency with percentages. Quantitative variables such as age, height, weight, BMI, graft size, length of stay in the hospital, percentage of graft take were summarized in terms of mean standard deviation. Effect-modifiers such as age, gender, BMI, smoking status, graft site, graft size, diabetes and hypertension will be controlled through stratification. Post-stratification independent t-test or Mann Whitney U test will be applied to compare percentage of graft take among two treatment groups. Post-stratification chi-square test will be applied to assess difference of post-operative complications among two treatment groups. P-value <0.05 was considered as statistically significant.